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CONNECTICUT      ; 

AGRICULTURAL  EXPERIMEHT  STATION 

NEW     HAVEN,    CONN. 


BULLETIN    139,    JULY,   1902. 


ENTOMOLOGICAL    SERIES,    No.     7. 


The    Apple-Tree   Tent-Caterpillar. 


CONTENTS. 

Page 
Officers  and  Staff  of  Station 2 

Apple-Tree  Tent-Caterpillar __ 3 

Abundance  in  Connecticut  in  1902 4 

Food  Plants 4 

Habits  and  Life  History 5 

Description 6 

Natural  Enemies 7 

Remedies 8 

Summary 11 

The  Bulletins  of  this  Station  are  mailed  free  to  citizens  of  Con- 
necticut who  apply  for  them,  and  to  others  as  far  as  the  limited  edi- 
tions permit. 


CONNECTICUT  AGRICULTURAL  EXPERIMENT  STATION, 

OFFICERS    .A-IISriD    STAFF. 


STATE   BOARD    OF    CONTROL. 

Ex  officio. 
His  Excellency  George  P.  McLean,  President. 

Appointed  by  Connecticut  State  Agricultural  Society: 
B.  W.  Collins,  Meriden. 

Appointed  by  Board  of  Trustees  of  Wesley  an  University: 
Prof.  W.  O.  Atwater,  Middletown. 

Appointed  by  Governor  and  Senate: 
Edwin  Hoyt,  New  Canaan. 
James  H.  Webb,  Hamden. 

Appointed  by  Board   of  Agriculture : 
T.   S.   Gold,  West   Cornwall,    Vice  President. 

Appointed  by  Governing  Board  of  Sheffield  Scientific  School: 
W.  H.   Brewer,  New  Haven,  Secretary. 

Ex  officio. 
E.  H.  Jenkins,  New  Haven,  Director  and  Treasurer. 


STATION    STAFF. 

Chemists. 
E.  H.  Jenkins,  Ph.D.,  Director.  T.  B.  Osborne,  Ph.D. 

A.  L.  Winton,  Ph.B.  A.  W.  Ogden,  Ph.B. 

I.  F.  Harris,  B.S.  M.  Silverman,  Ph.B. 

Botanist. 
G.  P.  Clinton,  S.D. 

Entomologist. 
W.  E.  Britton,  B.S. 

In  charge  of  Forestry  Work. 
Walter  Mulford,  F.E. 

Grass  Gardener. 
James  B.  Olcott,  South  Manchester. 

Stenographers  and  Clerks. 

Miss  V.  E.  Cole. 
Miss  L.  M.  Brautlecht. 

In  charge  of  Buildings  and  Grounds. 
William  Veitch. 

Laboratory  Helpers. 
Hugo  Lange.  William  Pokrob. 

Sampling  Agent. 
V.  L.  Churchill,  New  Haven. 


THE   APPLE-TREE    TENT-CATERPILLAR.  3 

THE  APPLE-TREE  TENT-CATERPILLAR. 

Clisiocampa  americana,  Harris. 
By  W.  E.  Britton,  State  Entomologist. 

One  of  the  chief  leaf-eating  enemies  of  the  apple  orchard  is 
the  tent-caterpillar.  Though  not  as  injurious  as  some  other 
pests,  it  is,  perhaps,  the  most  obvious  one,  for  by  it  the  trees 
are  stripped  of  their  foliage  early  in  the  season.  As  it  forms 
conspicuous  nests  on  the  wild  cherry  and  apple  trees,  its  pres- 
ence is  evident  to  all,  and  as  it  may  be  easily  destroyed  there 
is  really  no  excuse  for  allowing  it  to  attack  and  seriously  injure 
orchards.  This  insect  is  distinguished  from  others  that  feed 
upon  the  leaves  by  the  nests  or  tents  which  it  makes  on  the 
branches  early  in  May.  .  The  caterpillars  remain  inside  the  nest 
through  the  night  and  during  cloudy  weather,  coming  out  to 
feed  for  a  short  time  each  pleasant  day. 

Fruit  growers  are  apt  to  confuse  the  tent-caterpillar  with  the 
fall  web-worm,  an  insect  which  makes  nests  on  the  ends  of  the 
branches  of  fruit  and  forest  trees  during  August  and  Septem- 
ber. The  two  species  are  quite  different  and  can  easily  be 
distinguished  if  we  remember  that  the  former  occurs  only  in 
spring,  and  that  the  caterpillars  stay  inside  the  tent  in  bad 
weather,  but  go  out  of  it  to  feed.  The  fall  web-worm  appears 
in  late  summer,  and  the  feeding  is  done  wholly  within  the 
nest.  A  few  leaves  are  enclosed  in  the  web,  and  after  these 
have  been  eaten,  the  web  is  enlarged  to  include  fresh  leaves, 
which  in  turn  are  devoured.  Sometimes  an  entire  branch  is 
thus  enclosed  by  the  nest  of  the  fall  web-worm. 

The  tent-caterpillar  is  sometimes  wrongly  called  the  "bag- 
worm."  The  bag-worm  is  a  very  different  insect.  Bag-worms 
do  not  live  together  in  large  nests  like  tent-caterpillars,  but 
each  larva  forms  a  small  bag  or  case  from  one  to  two  inches 
long  in  which  the  body  is  enclosed.  The  entire  larval  period 
and  the  pupa  stage  are  passed  in  this  case  and  the  female  lays 
eggs  in  it  for  the  following  generation. 

The  apple-tree  tent-caterpillar  also  differs  from,  though 
closely  allied  to,  the  forest  tent-caterpillar,  which  has  caused 
much  injury  to  fruit,  shade  and  forest  trees  in  Vermont,  New 
Hampshire  and  northern  New  York  during  the  past  few  years. 


4  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    1 39.' 

Notwithstanding  its  name,  the  forest  tent-caterpillar  forms  no 
tent. 

The  apple-tree  tent-caterpillar  is  a  native  of  North  America 
and  probably  occurs  throughout  the  United  States  and  Canada, 
but  is  most  abundant  in  the  Eastern  States.  Though  damage 
by  this  insect  was  recorded  as  early  as  1646,  the  species  was 
first  named  and  described  by  Dr.  T.  W.  Harris  only  fifty 
years  ago. 

Abundance  in  Connecticut  in  1902. 

Though  the  nests  are  seen  every  spring  in  Connecticut,  the 
insect  has  not  usually  been  as  destructive  here  as  in  northern 
New  England. 

The  wild  cherry  furnishes  the  common  food  supply,  and  often 
the  injury  does  not  extend  to  apple  orchards. 

The  present  season,  however,  the  tent-caterpillar  has  been 
abundant  everywhere  and  has  attacked  not  only  cherry  and 
apple  trees,  but  several  other  kinds.  One  grower  reports  this 
as  the  most  troublesome  pest  on  his  peach  trees.  The  black 
cherry  trees  and  choke  cherry  bushes  along  roadsides  and 
hedge  rows  were  stripped  of  leaves.  According  to  our  obser- 
vations, the  outbreak  was  not  a  local  one,  but  occurred  over 
the  whole  State.  It  was  somewhat  more  severe  in  the  northern 
portion.  The  three  agents  employed  by  the  Station  to  gather 
fruit  statistics,  who  have  covered  the  entire  State  in  their  travels, 
have  reported  defoliated  trees  in  nearly  every  town.  The  writer 
has  made  similar  observations  in  those  portions  of  the  State 
in  which  he  has  occasion  to  travel. 

Moreover,  of  all  orchard  insects  the  tent-caterpillar  is  the 
most  commonly  reported  by  the  fruit  growers. 

Mr.  T.  S.  Gold  believes  that  the  insect  has  not  been  so 
abundant  for  sixty-six  years  or  since  the  terrible  ice  storm  of 
1836. 

Food  Plants. 

The  black  and  choke  cherry  are  the  favorite  and  probably 
the  natural  food-plants  of  the  species.  The  apple  is  the  next 
choice,  and  in  seasons  when  the  caterpillars  are  numerous 
orchards  are  attacked  and  sometimes  entirelv  defoliated.     Lowe 


LIFE    HISTORY    OF    THE    TENT-CATERPILLAR.  5 

mentions*  cherry,  apple,  plum,  peach,  rose,  witch  hazel,  beech, 
barberry,  oak,  willow  and  poplar  as  food  plants.  Weed  found 
the  caterpillars  feeding  upon  birch, f  and  the  writer  has  occa- 
sionally found  them  eating  the  leaves  of  various  species  of  oak. 

Habits  and  Life  History. 

The  eggs  are  laid  in  cylindrical  masses  encircling  small  twigs 
of  the  apple  and  cherry,  during  the  last  days  of  June  or  first 
of  July.  Specimens  in  breeding  cages  in  the  laboratory  laid 
eggs  soon  after  the  middle  of  June,  but  this  is  somewhat  earlier 
than  they  are  laid  upon  the  trees  out  of  doors.  After  deposit- 
ing a  ring  of  eggs  averaging  over  two  hundred  in  number,  the 
parent  moth  covers  the  eggs  with  a  viscid  fluid  which  hardens, 
giving  them  a  varnished  appearance.  The  eggs  are  probably 
greatly  protected  by  this  coating  from  the  weather  and  from 
predaceous  insects.     See  Fig.  I. 

The  eggs  do  not  hatch  until  the  following  April,  thus  remain- 
ing upon  the  twigs  for  about  nine  months.  The  tiny  cater- 
pillars first  feed  upon  the  frothy  mass  surrounding  the  eggs, 
and  next  attack  the  new  leaves  which  are  then  unfolding. 
After  a  few  days  they  spin  many  silken  threads  to  form  their 
nest,  usually  in  a  fork  of  the  branches. 

This  nest  or  colony  contains  the  caterpillars  from  a  single 
mass  of  eggs.  Except  when  feeding  they  remain  in  the  nest, 
but  when  nearly  full-grown,  the  caterpillars  may  often  be  found 
at  rest  on  the  outside  of  the  tent.  (See  Plate  II.)  They  spin 
threads  wherever  they  crawl  along  the  branches  from  the  nest 
to  their  feeding  places. 

The  egg-masses  do  not  all  hatch  at  the  same  time,  and  it  is 
not  uncommon  to  find  half-grown  and  newly-hatched  cater- 
pillars in  the  same  vicinity.  Mr.  J.  M.  Whittlesey,  of  Morris, 
Conn.,  states  in  a  letter  to  the  writer,  that  during  the  spring 
of  1902,  the  hatching  period  extended  over  nearly  twenty-one 
days. 

The  average  feeding  period  is  about  six  weeks,  during  which 
time  the  caterpillars  have  molted  or  cast  their  skins  several 
times.  As  they  increase  in  size  they  become  more  voracious 
and  devour  the  leaves  rapidly.     At  each  molting  period  they 

*  Bulletin  152,  N.  Y.  Agr.  Exp.  Station,  p.  281. 
f  Bulletin  38,  N.  H.  Agr.  Exp.  Station,  p.  53. 


6  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    1 39. 

stop  feeding  for  a  few  hours,  then  begin  again  with  renewed 
vigor. 

When  fully  grown  the  caterpillars  cease  eating  and  wander 
about  restlessly  for  a  day  or  two,  then  spin  white  silken  cocoons 
in  the  grass  under  the  trees,  in  the  crevices  of  the  rough  bark, 
or  about  buildings,  boxes,  etc.,  that  may  be  near  the  infested 
trees. 

There  is  only  a  single  brood  each  year. 

A  colony  of  tent-caterpillars  was  brought  into  the  laboratory 
on  May  1st.  The  nest  had  been  formed,  though  the  cater- 
pillars were  small,  measuring  about  three-sixteenths  of  an 
inch  in  length.  They  had  probably  been  hatched  about  a 
week  and  are  shown  on  Plate  I.  On  May  26th,  they  had 
become  full-grown  and  three  or  four  were  pupating.  In  a 
week  all  had  made  their  cocoons  and  by  the  16th  of  June  the 
adults  began  to  emerge.  This  continued  for  nearly  a  week, 
until  all  had  come  forth.  Meantime  several  egg-masses  had 
been  formed  in  the  breeding  cage  by  the  females. 

Description. 

Egg.  The  eggs  are  grey  in  color  and  very  small,  being 
about  one-eighteenth  of  an  inch  long,  and  slightly  more  than 
half  as  thick.  The  upper  end  is  circular,  and  is  slightly  larger 
than  the  lower  end.  They  are  placed  on  end,  close  together, 
and  covered  one-sixteenth  of  an  inch  deep  with  a  brown  sub- 
stance resembling  glue.  The  whole  mass  usually  encircles 
the  twig,  but  is  sometimes  deposited  on  one  side  only.  An  egg- 
mass  is  shown  in  Fig.  I. 

Larva.  When  first  hatched,  the  caterpillar  is  very  small 
and  nearly  black  with  a  few  grey  hairs. 

It  molts  five  or  six  times  as  it  increases  in  size,  and  after 
each  molt  the  markings  show  more  distinctly.  When  full- 
grown  the  caterpillar  is  from  two  to  two  and  one-half  inches 
in  length  and  is  thinly  covered  with  long  light-brown  hairs. 

The  color  is  black  with  a  white  stripe  along  the  back,  and 
many  short  irregular  brownish  stripes  or  markings  along  the 
side  of  each  segment.  The  sides  are  of  a  bluish  color  and  each 
segment  bears  an  oval  blue  spot  nearly  surrounded  with  black. 
The  under  side  of  the  body,  head,  and  legs  are  black.  A  full- 
^rown  larva,  natural  size,  is  shown  on  Plate  I. 


NATURAL    ENEMIES    OF   THE   TENT-CATERPILLAR.  J 

Pupa.  The  pupa  stage  is  passed  in  a  white,  oval  cocoon, 
which  is  about  one  inch  in  length  and  half  an  inch  in  thick- 
ness. It  is  made  of  silken  threads  spun  by  the  caterpillar 
and  loosely  woven.  It  is  usually  attached  by  one  side  to 
some  object  in  a  more  or  less  protected  place.  Plate  III 
shows  a  few  of  the  cocoons. 


Fig.   i. — Egg-mass  on  Apple  Twig  ;  natural  size. 

Adult.  The  adult  is  a  four-winged  moth  of  light  reddish- 
brown  color  with  two  whitish  stripes,  extending  obliquely  across 
each  fore  wing.  The  female  has  a  wing  expanse  of  about  one 
and  one-half,  and  the  male  about  one  and  one-eighth  inches. 
The  males  are  inclined  to  be  somewhat  darker  in  color  than  the 
females,  though  there  is  much  variation  in  the  intensity  of  the 
ground  color  and  of  the  markings  in  both  sexes. 

The  rear  wings  are  the  same  color  as  the  fore  wings,  but 
are  not  marked  with  white  stripes.  Both  sexes  are  shown 
on  Plate  III. 

Natural  Enemies. 

The  tent-caterpillar  is  usually  held  in  check  to  a  considera- 
ble extent  by  its  natural  enemies ;  in  fact,  but  for  them  it  would 


8  CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    1 39. 

be  much  more  abundant  and  destructive  each  season.  Its 
abundance  the  present  season  is  due  to  a  comparative  scarcity 
of  natural  enemies,  thus  allowing  the  species  to  multiply 
unchecked. 

An  ichneumon  fly,  Pimpla  inquisitor  Say.,  is  a  common  para- 
site of  the  tent-caterpillar,  and  there  is  a  bacterial  disease  which 
in  some  seasons  destroys  the  larvae  in  large  numbers.  If  the 
latter  is  prevalent,  large  numbers  of  dead  caterpillars  are  found 
about  the  trees  and  nests. 

Birds  are  important  factors  in  the  control  of  this  pest,  the 
cuckoos  playing  an  important  part.  The  crow,  chickadee, 
oriole,  chipping  sparrow,  yellow  warbler,  and  red-eyed  vireo 
are  other  birds  that  feed  upon  the  caterpillars. 

This  season  we  have  not  observed  the  presence  of  the  bac- 
terial disease,  or  unusual  abundance  of  the  ichneumon  para- 
sites,— while  the  trees  now  have  a  great  number  of  egg-masses, 
indicating  that  the  insect  will  be  abundant  next  season. 
Farmers  and  fruit  growers  should  therefore  be  ready  to  com- 
bat it. 

Remedies. 
Destroying  the  Eggs. 

Much  can  be  done  through  the  winter  months  in  destroying 
the  egg-masses.  When  the  trees  are  bare  these  can  be  seen 
near  the  ends  of  the  twigs,  and  may  easily  be  clipped  off  by 
means  of  a  tree  pruner  having  a  long  handle,  which  enables 
the  operator  to  reach  and  cut  off  the  egg  masses  while  stand- 
ing upon  the  ground.  These  should  then  be  gathered  and 
burned. 

Professor  Weed  recommends  that  children  be  given  a  small 
bounty  for  gathering  egg-masses  and  cites  a  case  in  Newfields, 
N.  H.,  where  they  were  offered  ten  cents  per  hundred  clusters, 
by  the  village  improvement  society.  .  8,250  egg  masses  were 
collected,  and  if  each  cluster  contained  150  eggs,  which  is  a 
small  average,  1,237,500  eggs  were  destroyed  at  a  cost  of 
$8.25.* 

Many  writers  advise  the  destruction  of  the  wild  cherry  and 

*  Bulletin  17,  New  Series,  Division  of  Entomology,  U.  S.  Department 
of  Agriculture,  p.  77. 


REMEDIES    FOR   THE    TENT-CATERPILLAR.  9 

seedling  apple  trees,  which  harbor  the  tent-caterpillar  along  the 
hedge-rows  and  roadsides. 

If  not  destroyed,  the  owner  should  certainly  care  for  these 
trees  to  the  extent  of  keeping  them  free  from  insects,  and  not 
allow  them  to  be  a  menace  to  his  neighbor  or  the  orchards 
of  the  vicinity. 


Fig.  2. — a,  Waters'  Tree  Pruner  ;  b,  Henry's  Tree  Pruner. 


Brushing  off  the  Nests. 

Twenty  years  ago  the  writer  used  to  be  sent  through  the 
orchards  with  a  brush  mounted  on  the  end  of  a  pole  to  remove 
the  nests  from  the  trees  in  the  early  morning  or  on  a  cloudy 
day  when  the  caterpillars  were  in  them. 

The  brush  was  made  of  stiff  bristles  twisted  in  heavy  wire  and 
trimmed  to  the  shape  of  a  cone  about  six  inches  long.  It  was 
made  for  the  purpose,  and  worked  admirably. 

The  operator  stands  upon  the  ground,  inserts  the  point  of 
the  brush  in  the  nest  and  gives  it  a  few  turns,  and  the  entire 
nest  with  contents  is  wound  upon  the  brush.  The  cater- 
pillars may  then  be  easily  destroyed  by  crushing  upon  the 
ground. 


IO         CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    I39. 

During  recent  years  I  have  not  been  able  to  find  this  brush 
on  the  market,  but  the  M.  Leiner  Company  of  1250  Brook 
avenue.  New  York,  has  been  making  some  samples  after  my 
specifications  and  will  be  prepared  to  manufacture  it  in  the 
future  if  there  is  a  demand  for  it.  The  cost  will  be  less  than 
fifty  cents  at  wholesale  or  even  in  dozen  lots.  Local  dealers 
and  seedsmen  should  procure  a  supply  and  be  ready  to  sell  them 
to  fruit  growers  next  spring.  The  appearance  of  the  brush  is 
shown  in  Figure  3. 


■    I 


Fig.  3. — A  caterpillar  brush. 

Burning. 

Some  fruit  growers  practice  burning  the  nests  on  the  trees 
and  for  this  purpose  an  asbestos  torch  has  been  designed  and 
manufactured.  The  torch  is  filled  or  covered  with  kerosene, 
lighted,  and  held  under  the  nest  when  the  caterpillars  are  inside. 
We  do  not  recommend  burning,  because  there  is  danger  of 
severe  injury  to  the  tree.  Where  the  nests  are  near  the  ends 
of  the  branches  the  damage  may  be  very  slight,  but  as  the  tent- 
caterpillars  often  make  their  tent  at  the  fork  of  comparatively 
large  branches,  it  cannot  be  burned  without  danger  of  killing 


PLATE   I. 


A  full-grown  Caterpillar.     Natural  size. 
Photo,  by  B.   H.    Walden. 


Young  Caterpillars  in  nest. 
Photo,  by  B.  H.    Walden. 


PLATE   II. 


Caterpillars  resting  on  the  ontside  of  the  nest. 
Photo,  by  B.   H.    Walden. 


PLATE   II 


Male  and  female  moths.     Natural  size. 
Photo,  by  B.  H.    Walden. 


Cocoons  of  the  Tent-Caterpillar.     Natural  size. 
Photo,  by  B.   H.    Walden. 


SUMMARY.  I  I 

these  branches.  Brushing  off  the  nests  with  a  caterpillar  brush 
is  just  as  expeditious  as  burning  and  there  is  no  danger  of 
injuring  the  trees. 

Spraying. 

Where  the  orchardist  practices  early  spraying  no  other 
remedy  need  be  considered.  Arsenate  of  lead  or  Paris"  green, 
with  or  without  Bordeaux  mixture,  applied  to  the  foliage  will 
kill  the  caterpillars.  The  chief  difficulty  lies  in  the  fact  that 
some  of  the  caterpillars  hatch  and  begin  feeding  as  early  as 
the  first  leaves  appear  and  before  there  is  really  any  leaf-surface 
to  poison;  some  damage  may  be  done  before  spraying  begins. 
But,  as  the  caterpillars  eat  very  little  at  first,  this  damage  is 
not  liable  to  be  serious.  These  early  colonies  may  be  brushed 
from  the  trees,  and  the  spray  depended  on  to  kill  the  later 
ones. 

A  half  pound  of  Paris  green  or  three  pounds  of  arsenate 
of  lead  should  be  used  for  each  50  gallons  of  water  or  the  same 
quantity  of  Bordeaux  mixture.  Where  Paris  green  is  used 
without  Bordeaux  mixture,  three  pounds  of  fresh  lime  to  one 
of  poison  should  be  used  to  prevent  burning  the  leaves.  As 
the  Bordeaux  mixture  contains  plenty  of  lime,  no  more  is 
needed  in  connection  with  it.  Arsenate  of  lead  is  perfectly 
insoluble  in  water,  does  not  injure  foliage,  and  therefore  does 
not  need  the  addition  of  lime.  Paris  green  contains  a  little  free 
acid  which  is  soluble  in  water,  and  which  unless  neutralized 
may  burn  the  foliage. 

Summary. 

1.  The  apple-tree  tent-caterpillar,  a  native  insect  and  one 
of  the  chief  leaf-eating  enemies  of  the  orchard,  has  been  very 
abundant  throughout  Connecticut  the  present  season  and  has 
injured  fruit  trees  by  defoliating  them  in  May.  Wild  cherry 
is  probably  the  natural  food  of  the  species,  but  when  abundant 
it  attacks  apple  and  other  fruit  trees. 

2.  Eggs  are  laid  on  the  twigs  of  the  food  plant  in  summer 
and  hatch  the  following  April.  After  a  few  days  the  young 
caterpillars  form  on  the  branches  a  nest  in  which  they  live, 
2,-oino-  out  from  it  to  feed.     Thev  are  alwavs  within  the  nest 


12         CONNECTICUT    EXPERIMENT    STATION,    BULLETIN    I39. 

at  night  and  in  cloudy  weather.  They  become  full-grown 
in  about  six  weeks  and  spin  white  silken  cocoons  from  which 
the  adults  emerge  two  weeks  later. 

3.  The  small  grey  eggs  are  deposited  in  masses  of  200  or 
more  encircling  the  twigs,  and  are  covered  with  a  brownish 
substance.  The  full-grown  caterpillar  is  over  two  inches  long, 
black  above  and  below,  and  blue  on  the  sides,  with  a  white 
stripe  along  the  back.  It  is  thinly  covered  with  light  brown 
hairs.  The  white  cocoon  is  about  one  inch  in  length  and  half 
an  inch  in  thickness.  The  adult  is  a  reddish-brown  moth  with 
two  whitish  stripes  extending  obliquely  across  each  fore  wing. 

4.  The  species  is  usually  held  in  check  by  its  natural  enemies, 
which  consist  of  several  kinds  of  birds,  parasitic  insects  and  a 
bacterial  disease. 

5.  The  remedies  are:  to  gather  and  destroy  the  egg-masses 
during  the  winter  months;  spray  when  the  leaves  appear,  using 
three  pounds  of  arsenate  of  lead  or  one-half  pound  of  Paris 
green  to  50  gallons  of  water  or  Bordeaux  mixture;  if  imprac- 
ticable to  spray,  brush  off  the  nests  as  soon  as  they  can  be 
found,  choosing  the  early  morning  or  cloudy  weather,  when 
the  caterpillars  are  inside  the  nest;  burning  the  nests  on  the 
trees  is  not  to  be  recommended. 


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